BGB-3111 is a potent, specific and irreversible inhibitor of Bruton's tyrosine kinase (BTK). It would appear to be one of the structures claimed in Beigene patent US20150005277 [2], and may be the compound designated as I-2 therein (the R stereoisomer), which has a slightly higher potency vs. BTK than the S stereoisomer. However, this structure remains preliminary until full disclosure in peer reviewed literature.